Contact interaction and hot pressing of ZrB2-MoSi2 in CO/CO2 atmosphere

ZrB2-15 vol% MoSi2 ceramics were hot pressed in CO/CO2 atmosphere in the 1700-1900oC temperature range. During hot pressing, MoSi2 decomposes into Mo and Si and the phase composition of the as-sintered ceramic results in ZrB2, (Zr, Mo)B2, SiC, SiO2, and MoB. Contact melting between ZrB2 and MoSi2 was observed at 1800oC, corresponding to the formation of (Zr, Mo)B2. Ceramics obtained at1800-1850oC had - 500 \MPa and 200 MPa strength at room at 1800oC in vacuum, respectively. The thickness of the oxidized scales upon exposing the samples at 1600 oC for 120 min was 30-80 mu m and depended on the amount of residual MoSi2 and (Zr, Mo) B2. The highest oxidation resistance was observed for the ceramic sintered at 1850 degrees C.

Automated summary

ZrB2-15 vol% MoSi2 ceramics were hot pressed in CO/CO2 atmosphere in the 1700-1900oC temperature range. During hot pressing, MoSi2 decomposes into Mo and Si, resulting in the phase composition of ZrB2, (Zr, Mo)B2, SiC, SiO2, and MoB in the as-sintered ceramic. Contact melting between ZrB2 and MoSi2 occurs at 1800oC, forming (Zr, Mo)B2. The ceramics sintered at 1800-1850oC exhibited - 500 \MPa and 200 MPa strength at room temperature and in vacuum at 1800oC, respectively. The thickness of the oxidized scales after exposure at 1600 oC for 120 min ranged from 30-80 μm and depended on the amount of residual MoSi2 and (Zr, Mo) B2. The ceramic sintered at 1850 degrees C displayed the highest oxidation resistance.